Pontoon type floating tank roof



June 12, 195e J. H. wlGGlNs PoNTooN TYPE'FLOATING TANK RooF Filedqune 5, 1953 ATTORNEY United States PatentO PONTOON TYPE FLOATIN G TANK ROOF John H. Wiggins, Chicago, lil.

Application June 5, 1953, Serial No. 359,913

4 Claims. (Cl. 220-26) This invention relates to pontoon floating tank roofs of the kind that comprise a center pontoon and a peripheral pontoon, arranged in spaced, concentric relation and attached to the inner and outer edges, respectively, of a single deck of annular form that bridges the space between said pontoons.

The main object of my invention is to provide a floating tank roof of the general type or kind mentioned, which is of such design that when used in a tank of relatively great diameter, for example 150 or more, the deck will normally be maintained in a condition or position that insures efficient drainage of same thereby preventing painted surfaces on the deck from being injured by puddles of water that may collect thereon, and also increasing the stability of the roof and preventing it from being sunk by an abnormal liquid load that has collected on the deck as the result of said deck springing a leak, or as a result of the water outlets from the deck becoming clogged.

To thisend I have devised a floating tank roof of the general type mentioned, that is equipped with a means which performs the function of a load member that eX- erts a downward force or pressure on the deck at such a point as to, in effect, divide it into two downwardly sloped drainage surfaces that discharge into a circumferentially disposed gutter portion from which one or more Water discharge conduits lead.

Figure l of the drawings is a vertical, transverse sectional view illustrating one form of my invention, said View being taken on the line 1-1 of Figure 2.

Figure 2 is a fragmentary, top plan view of the roof shown in Figure l.

Figure 3 is an enlarged, transverse sectional Vview il lustrating how the circumferentially disposed gutter portion may include an annular trough member of substantially channel shape in cross section combined with the deck in such a way that the bottom of said trough member is considerably lower than the downwardly sloped drainage surfaces of the deck between which said member is arranged.

Figure 4 is an enlarged, transverse sectional view illustrating how the gutter portion may be formed by breaking the deck of the roof into two separate parts joined together by an annular weld which on cooling, causes the metal deck plates at opposite sides of said weld to assume such a form or shape that when the deck is depressed by the weight of the load member there is produced a substantially V-shaped gutter located between and at the lower ends of two downwardly sloped drainage surfaces, and

Figures 5 and 6 are sectional views illustrating different ways of combining the load member with the deck of the roof.

Referring to Figures l and 2 of the drawings, the reference character A designates the peripheral pontoon of the roof which preferably is of annular form and arranged in spaced, concentric relation with a circular, center pontoon B, and C designates a flexible diaphragm- ICC like deck attached at its outer and inner edges to the pontoons A and B respectively. A load member D extends circumferentially around the roof and is arranged on the top side of the deck intermediate the center pontoon B and peripheral pontoon A, so as to depress the central portion of the deck more than the normal amount below the level 10 of the liquid on which the roof oats, and thereby produce two eicient drainage surfaces C1 and C2 that discharge into a gutter portion which eX- tends circumferentially around the deck, said gutter portion being designated by the reference character E. Said load member D may be of annular form or of polygonal shape and it can be constructed in various ways and combined with or mounted on the deck in various ways. Also the gutter portion of the deck can be of similar shape or form in general outline.

In the form of my invention shown in Figures l and 2 the deck C is formed by a flexible or limber annular member that bridges the space between the center pontoon and peripheral pontoon, and the load member D is arranged above the top side of said deck and attached to same, preferably about midway the pontoons A and B. Said load member is illustrated as being formed by an annular rim or vertical web member 14 projecting upwardly from the deck between the downwardly sloping drainage surfaces C1 and C2 and having a housing member 13 attached to same as shown in Figure l, so as to produce a receptacle that is lled with concrete 22 or some other suitable relatively heavy, inexpensive substance that can be poured into the receptacle and preferably allowed to harden into a solid mass. As shown in Figure l the load member D is arranged directly above and in spaced relation with the gutter portion of the deck, and hence any refuse that collects in the trough portion E can be easily removed therefrom. Drain holes similar to the drain holes 27 shown in Figure 4 are formed in the lower end portion of the rim or web member 14 so that water which collects at opposite sides of said rim will seek a common level in the gutter portion or circumferential depression E in the deck, and one or more water discharge conduits 25 are provided for conveying water away from said depression or gutter portion. In Figure 6 of the drawings the load member D is shown as being composed of a channel shaped housing 20 lled with concrete 22 reinforced by bars or similar devices 21 and securely anchored to the housing by hooks 26 thereon that are embedded in the concrete, the housing 20 being mounted at the upper end of a web member 24 which is provided in its bottom edge portion with drain holes 27 through which water in the gutter can seep from one side to the other of said web member 24. Insteadof using a rim or web member 24 to support the load member D and attach it to the deck of the roof, said load member can be mounted on uprights or posts 23 arranged in spaced relation around the circumference of the roof as shown in Figure 5.

The deck of the roof can be formed by a limber or exible member, fabricated from metal plates, that eX- tends continuously from the peripheral pontoon to the center pontoon as shown in Figure l. Or a circular cut can be formed in the deck and the two parts of the deck lapped and joined together by a weld 15 shown in Figure 4, which extends circumferentially around the deck. The weld 15, due to contraction when it cools, picks up the deck plates at opposite sides of the weld and changes the shape of same in such a way that when the deck is depressed by the weight of the load member there is produced a substantially V-shaped gutter whose opposite sides have a suciently sharp downward pitch or slope to insure eicient drainage of the surfaces C1 and C2 that discharge into the trough E.

Still another way of constructing the trough portion of the roof is illustrated in Figure 3, wherein the reference 'character -19 ydesignates 'a vpreformed Aannular lrnember of substantially trough shape in cross section, arranged between thedrainage surfaces C1 and C42 of the deckand joined to samefby Welds 16, said trough 'member r19 extending continuously around thecircumference 'of the deck. This is the preferred wayof constructing the deck because the bottom of the trough member 19 is located in a plane that is considerablylower than the discharge edges of l'thedownwardly 'slopeddrainage surfaces C1 and Czthereby insuring'rapid and eicient drainage of tlie'top side of the roof 'and increasing the stability of the roof, by reason'of'the fact that ay large rain load is concentrated on a circumferentiallydisposed trough portion of 'the deckthat islocated between'thepontoo'ns A and B and whichvis provided with a bottom that is enough lower than theidrainage surfaces C1 anl'C2 practically eliminate the ypossibility of water that has collected inthe trough frornoverflowing onto said drainage surfaces when the trough is properly drained. At a trifling expense the trough member 19 may be made thicker than the drainage parts C1 and C2 of the deck for corrosion allowance.

The tank in which the roof is arranged is of conventional construction and is provided with a cylindrical side wall 1 and a flat bottom 2. The peripheral'pontoon A is composed of two concentrically arranged rims .3 and 4 attached to bottom and top members 5' and 6, and the center pontoon B is of circular form and is composed of an annular rim 9 attached at its lower end t0 a bottom member 7 and at its upper end to a cone shaped top member 8. In Figure 1 the arrows indicate the direction of flow of rain water that falls on the top side of the roof and which is conducted away from same and discharged at apoint on the exterior of the tank.

In a oating tank roof of the construction above described, the intermediate load D enhances the drainage characteristics of the roof because it extends around the entire circumference of the deck and depresses the intermediate gutter portion of the deck C much more than normal, thereby increasing the pitch of drainage surfaces that slope downwardly from the center pontoon and peripheral pontoon and discharge into said gutter portion;` it lowers the center of gravityof the deck and makes the roof more stable due to the fact that any rain water that falls on the roof, immediately flows into a trough portion that extends continuously around the entire circumference of the deck, and still another desirable characteristie of such a roof is that dirt and trash can'easily be removed from the trough portion of same due to the fact that the load member is arranged above and in widely spaced relationship with the trough portion of the deck.

Having thus described my invention what I claim and desire to secure by Letters Patent is the following:

1. A oating roof for a liquid containing tank comprising, a center pontoon arranged to oat on the liquid adjacent to the center of the tank, a peripheral pontoon arranged to float on the liquid adjacent to the wall of the tank, said peripheral pontoon being disposed concentrically about said center pontoon and in spaced apart relationship with respect thereto, an annular tiexible diaphragm-like deck joining said pontoons and providing a liquid-tight cover therebetween, said diaphragm-like deck having inner and outer annular portions of substantially equal and opposite pitch, said outer deck portion being joined to said peripheral pontoon substantially at the liquid level'in "the tank and'extending radially inwardly and downwardly therefrom and said inner deck portion being joined to said center pontoon substantially at the liquid level in the tankand extending radially outwardly and downwardly therefrom so that at least a major portion of said diaphragm-like deck is in direct buoyant contact with the liquid in the tank and disposed below the level thereof and so that said oppositely pitched inner and outer deck portions provide an annular gutter located substantially concentrically and midway with respect to said pontoons for the collection of rain and snow that may fallon said roof, an annular load member carried by said deck in the area of said gutter and disposed thereabove, said load member being of suiiicient weight and so distributed substantially uniformly to retain the area of said gutter below the level of the liquid in the tank in order to maintain the pitch of said inner and outer deck portions and to prevent said diaphragm-like deck from being flexed materially upwardly by the `force of the liquid in Contact with the underside thereof, and means for draining the collected rain and snow from said gutter.

2. Theoating roof construction set forth in claim l, wherein said annular gutter is defined by complementary adjacent annular sections of said respective inner and youter deck portions.

3. The floating roof construction set forth in claim 1, wherein said annular gutter is defined at least partially by a separate annular trough-like member joined to adjacent annular sections of said respective inner and outer deck portions.

4. The floating roof construction set forth in claim l, wherein said annular load member is disposed in superposed relation with respect to said gutter and positioned sufliciently thereabove to accommodate the removal of refuse that may collect in said gutter.

References Cited inthe tile of this patent UNITED STATES PATENTS 1,919,634 Haupt et al. July 25, 1933 2,282,772 Wiggins May 12, 1942 2,321,058 Wiggins lune 8, 1943 2,464,786 Allen Mar. 22, 1949 2,497,047 Prager'et al. Feb. 7, 1950 2,586,856 Orr et al. Feb. 26, 1952 2,605,014 Wiggins et al. July 29, 1952 2,606,684 Wiggins Aug. 12, 1952 2,663,453 Wiggins et al. Dec. 22, 1953 

